cpufreq: interactive: take idle notifications only when active
cpufreq: interactive: take idle notifications only when active

Register an idle notifier only when the governor is active.  Also
short-circuit work of idle end if the governor is not enabled.

Signed-off-by: Sam Leffler <771765c27e4a0a8dc00f0c2f551d06e8bc1a9ada@chromium.org>
Change-Id: I4cae36dd2e7389540d337d74745ffbaa0131870f

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas